Sonography vs. excretory urography in acute flank pain

A prospective study compared the diagnostic accuracy of sonography and excretory urography in determining the cause of acute flank pain in 61 patients. Forty-one patients had urinary tract stone disease. Of these, five had nonobstructing renal stones and 36 had obstructing stones. A correct diagnosis was made by urography in 85% and by sonography in 66%. Small stones at the ureterovesical junction were more accurately diagnosed by sonography (79%) than by urography (68%). In all the patients where sonography failed to detect the offending stone, the stone was calcified and evident on the plain radiographs. There were no false-positive diagnoses in the patients clinically judged to have passed a renal stone (nine patients) or whose pain was arising outside of the urinary tract (five patients). Neither sonography (17%) nor urography (50%) was accurate in diagnosing acute pyelonephritis in the six patients with this diagnosis. Although sonography is not as accurate overall as urography in acute flank pain, it is a viable alternative in those with recurrent renal colic due to stone disease and in the pregnant patient.     

Ultrasonic diagnosis of ureteral calculi in patients with acute flank pain

The diagnostic value of ultrasonography (US) and intravenous urography has been compared in a prospective study comprising 123 consecutive patients with severe acute flank pain of less than 72 hours' duration. Ultrasonography was performed transabdominally with a 5 MHz sector real-time transducer. Ureteral calculi were considered the final diagnoses in 46 patients, of which 35 with and 11 without accompanying hydronephrosis. Ureteral calculi were correctly diagnosed by US in 17 patients (sensitivity 37%). If hydronephrosis with or without calculus is included as a positive sign of ureteral calculus, a correct diagnosis was suggested by US in 34 patients (sensitivity 74%). We consider US to be a valuable method in patients with previous contrast media reactions, but recommend urography as the standard imaging method when renal colic is clinically suspected.     

Radiologic investigation of renal colic: unenhanced helical CT compared with excretory urography.

OBJECTIVE: Our aim was to compare unenhanced helical CT and excretory urography in the assessment of patients with renal colic. SUBJECTS AND METHODS: Fifty-three of 70 consecutive patients with acute signs of renal colic were prospectively examined with unenhanced helical CT, which was followed immediately by excretory urography. Two radiologists who were unaware of the findings independently interpreted these examinations to determine the presence or absence of ureteral obstruction. On all CT scans that had positive findings for ureteral stones or obstruction, we looked for secondary signs of obstruction (perinephric or periureteral fat stranding, ureteral wall edema, ureteral dilatation, and blurring of renal sinus fat). RESULTS: A stone was recovered in 45 of the 53 patients, nine before and 36 after imaging. The latter 36 patients had their stones identified on CT, whereas only 24 patients had their stones identified on excretory urography. Eight patients without stone disease had normal ureters on both CT and excretory urography. Of the 45 patients who had stone disease, 26 had ureteral dilatation on both CT and excretory urography, and 36 patients who recovered a stone after CT had secondary signs of obstruction. Of the nine patients who recovered a stone before CT, three had secondary signs of obstruction. Two patients had periureteral fat stranding, ureteral wall edema, and renal sinus fat blurring. One patient had only ureteral wall edema. CONCLUSION: Compared with excretory urography, unenhanced helical CT is better for identifying ureteral stones in patients with acute ureterolithiasis. Secondary CT signs of obstruction, including renal sinus fat blurring, were frequently present even when the stone was eliminated before imaging.     

Ultrasonography in the diagnosis of hydronephrosis in patients with normal renal function

In order to define the sensitivity and specificity of ultrasonography (US) in the diagnosis of hydronephrosis, 125 patients with normal renal function were examined after urography using high-resolution real-time scanning. The overall diagnostic accuracy of US in detecting hydronephrosis was 85.2%, with a specificity of 84.4% and a sensitivity of 89.9%. It is concluded that US may be considered the screening test of choice for the diagnosis of hydronephrosis. However, urography is still required for the evaluation of renal function, site, and nature of the obstruction when US shows a dilated collecting system and in the patient with a normal US but renal colic.     

Patients with acute flank pain: comparison of MR urography with unenhanced helical CT

PURPOSE: To compare unenhanced helical computed tomography (CT) and magnetic resonance (MR) urography, by using T2-weighted and contrast material-enhanced T1-weighted imaging to examine patients with acute flank pain, with reference to excretory urography and final clinical diagnosis. MATERIALS AND METHODS: Forty-nine patients underwent CT, MR urography (with T2-weighted and gadopentetate dimeglumine-enhanced T1-weighted sequences), and excretory urography. CT and MR urographic findings were evaluated separately and independently by two radiologists each (CT, observers A and B; MR urography, observers C and D) for the presence, cause, level, and degree of obstruction. The final conclusive diagnosis was based on the combination of excretory urographic, clinical, and interventional results. RESULTS: At final diagnosis, 32 (65%) patients were found to have ureteral stones causing unilateral obstruction. In ureteral stone detection, the sensitivity and specificity of CT were 90.6% (29 of 32 patients) and 100.0% (17 of 17 patients), respectively (observer A) and 90.6% (29 of 32 patients) and 94.1% (16 of 17 patients), respectively (observer B), while those of MR urography were 93.8% (30 of 32 patients) and 100.0% (17 of 17 patients), respectively (observer C) and 100.0% (32 of 32 patients) and 100.0% (17 of 17 patients), respectively (observer D). Spearman correlation coefficients for stone size at CT were 0.76 (P <.001) and 0.75 (P <.001) and at MR urography, 0.49 (P =.005) and 0.51 (P =.004). CONCLUSION: In routine clinical practice, CT is the modality of choice in the evaluation of patients with acute flank pain. MR urography is an accurate and suitable alternative imaging technique in selected patients.     

Acute ureterolithiasis: nonenhanced helical CT findings of perinephric edema for prediction of degree of ureteral obstruction

PURPOSE: To determine whether the extent of perinephric edema on helical computed tomographic (CT) images without contrast material enhancement can be used to predict the degree of ureteral obstruction in patients with acute ureterolithiasis. MATERIALS AND METHODS: Nonenhanced helical CT and excretory urographic images in 82 patients with flank pain were retrospectively reviewed. For each patient, a radiologic diagnosis was established, and the degree of ureteral obstruction determined on urograms was compared with the extent of perinephric edema assessed on CT images. RESULTS: None of 29 patients with no abnormalities seen at urography had evidence of perinephric edema at CT. Of six patients with noncalculous disease, two with acute pyelonephritis had perinephric edema at CT. Of 47 patients with acute ureterolithiasis, eight had no perinephric edema at CT and a nonobstructing calculus at urography, 21 had limited edema at CT and low-grade obstruction at urography, and 15 had extensive edema at CT and high-grade obstruction at urography. Three patients had extensive perinephric edema at CT but low-grade obstruction at urography. The extent of edema allowed accurate prediction of the degree of ureteral obstruction in 44 (94%) of 47 patients with acute ureterolithiasis. CONCLUSION: The extent of perinephric edema on nonenhanced helical CT images can be used to predict the degree of ureteral obstruction in acute ureterolithiasis.     

Sensitivity of gray scale ultrasound in detecting urinary tract obstruction.

To determine the reliability of gray scale ultrasound in detecting urinary tract obstruction, a prospective study of 67 patients examined by both excretory urography and ultrasound was undertaken. The degree of hydronephrosis was defined by urographic criteria, and the corresponding echograms were analyzed without knowledge of the urographic results. Hydronephrosis was correctly diagnosed by ultrasound in 46 of 47 kidneys shown to be obstructed on urography, for a sensitivity of 98%. Our results show that when obstruction is the sole clinical question, ultrasound is an effective screening test. Thus many patients with a variety of medical diseases of the kidney can be spared excretory urography.     

Renal colic: diagnosis and outcome.

To assess whether ultrasonography (US) with or without plain abdominal radiography (kidney, ureter, bladder [KUB] radiography) can replace intravenous urography (IVU) in detection of acute urinary tract obstruction, 101 consecutive patients with renal colic were evaluated with US followed immediately by IVU. Receiver operating characteristic (ROC) curves for US diagnosis of acute urinary tract obstruction yielded sensitivities of 91% and 92% for two reviewers at a specificity of 90%. There was no statistically significant difference between US and IVU results. When US was combined with KUB radiography, ROC curves yielded sensitivities of 94% and 97% for two reviewers at a specificity of 90%.KUB radiography alone was of limited diagnostic value. For US alone, no false-positive results occurred, and the false-negative results (n = 9 and n = 6 for two reviewers) were encountered in cases of grade 1 hydronephrosis and nondilated obstructive uropathy. The authors conclude that US combined with KUB radiography can replace IVU in initial evaluation and follow-up of the great majority of patients with renal colic.     

Assessment of painful ureterohydronephrosis during pregnancy by MR urography

The purpose of this study was to assess the value of the fast imaging sequence called RARE (rapid acquisition with relaxation enhancement) MR urography (or RMU) In pregnant women with painful ureterohydronephrosis. A total of 17 pregnant women with an acute flank pain were examined with RMU. Results were compared with those of US, X-rays and the evolution of symptoms. The gold standard techniques used to evaluate the results of MR urography were US when it showed the entire dilated urinary tract and the nature of the obstruction (9 cases), limited intravenous urography (IVU) when performed (3 cases) or endoscopic procedure (5 cases). The accuracy of RMU in the detection of urinary tract dilatation and the localization of the level of obstruction was excellent (sensitivity 100% in our series). The determination of the type of obstruction, intrinsic vs extrinsic, was always exact. The RMU technique alone could not specify the exact nature of the obstruction. The RMU technique is able to differentiate a physiological from a pathological ureterohydronephrosis during pregnancy. It could be considered as the procedure of choice when US failed to establish the differential diagnosis.Correspondence to: C. Roy     

Acute flank pain: comparison of unenhanced helical CT and ultrasonography in detecting causes other than ureterolithiasis

Several conditions can clinically mimic renal colic. We assessed the accuracy of non-contrast-enhanced helical CT and of ultrasonography (US) in offering an alternative explanation for flank pain. In a 3-year period, 181 patients with acute flank pain underwent US and non-contrast-enhanced helical CT in a blinded sequence. Their efficacy in detecting both alternative causes of pain and additional findings unrelated to the pain was assessed in 160 cases with a confirmed diagnosis. An alternative cause was found in 23 cases (14%). US gave 4 false-negative results (1 acute appendicitis, 1 ovarian cyst torsion, 1 diverticulitis, and 1 papillary necrosis) and 2 false-positive results (1 acute pyelonephritis and 1 diverticulitis), with a 78% sensitivity and a 98% specificity for nonlithiasic causes. CT gave 5 false-negative results (1 complicated ovarian cyst, 1 pleuritis, 1 epididymitis, 1 acute pyelonephritis, and 1 papillary necrosis) and 1 false-positive (1 simple ovarian cyst described as a complicated lesion), resulting in a 74% sensitivity and a 99% specificity for diagnosing alternative causes. There were 130 additional US findings in 68 patients and 151 additional CT findings in 77 patients. A wide spectrum of findings can be identified in subjects imaged for flank pain. Non-contrast-enhanced helical CT and US have comparable accuracy in diagnosing causes other than stone disease. Electronic Publication     

Ultrasound of the kidney: obstruction and medical diseases

Ultrasound has emerged as the primary imaging modality in conditions where either renal obstruction or renal medical disease is suspected on the basis of clinical and laboratory findings. In urinary tract obstruction, pathophysiologic changes affecting the pressure in the collecting system and kidney perfusion are well understood and form the basis for the correct interpretation of real-time US and color Doppler duplex sonography (CDDS). Ultrasound is very sensitive for the detection of collecting system dilatation ("hydronephrosis"); however, obstruction is not synonymous with dilatation, as either obstructive or nonobstructive dilatation may be present. To differentiate these conditions, CDDS with measurement of the resistive index (RI) in the intrarenal arteries is extremely helpful, as obstruction (except in the peracute stage) leads to intrarenal vasoconstriction with a consecutive increase of the RI above the upper limit of 0.7, whereas nonobstructive dilatation does not. Diuretic challenge to the kidney may further enhance these differences in RI between obstruction and dilatation. Based on these findings, the present value of US and CDDS in the assessment of the patient with flank pain or renal colic is suggested, especially with respect to promising results for spiral CT and based on cost analysis. In renal medical disease, distinguishing different pathologic conditions using gray-scale US and CDDS (RI) criteria is still very difficult. Nevertheless, US is the fist-line imaging modality in the patient with renal insufficiency. Electronic Publication     

Imaging in ureteral complications of renal transplantation: value of static fluid MR urography

Ureteral obstruction is an infrequent complication after renal transplantation that may cause rapid loss of transplant function. We tested static fluid MR urography for determining the cause of graft hydronephrosis. Magnetic resonance urography was performed in nine transplants with dilated collecting systems on ultrasound. A heavily T2-weighted 3D turbo spin-echo sequence on a 1.5-T scanner was used and maximum intensity projections were obtained. The patients also underwent excretory urography (n = 1), renal scintigraphy (n = 1), antegrade pyelography (n = 3), voiding cystourethrography (n = 4), and non-enhanced CT (n = 2). Six patients had pathologic conditions including ureteral stricture, compression by lymphoceles, implantation stenosis, vesicoureteral reflux, and late-occurring transitional cell carcinoma at the implantation site. Static MRU was able to diagnose or exclude a dilation of the graft collecting system. It visualized the course of the ureters and localized the obstruction site in four of five obstructed transplants. In one case the ureter was obscured by lymphoceles, which were demonstrated by hydrographic MRU as well. The definite cause for obstruction was provided in only 2 of 5 cases. Dilation due to vesicoureteral reflux could not be differentiated. The current multimodality approach to renal transplant imaging already provides comprehensive assessment of graft hydronephrosis. Static MRU may be useful in some cases since complications associated with intravenous iodinated contrast or antegrade pyelography can be avoided. Its main drawback, the lack of functional information, may be overcome by combining it with contrast-enhanced MRU. Received: 18 February 1999; Revised: 23 July 1999; Accepted: 18 November 1999     

Emergency excretory urography in blunt abdominal trauma

In a prospective study the authors correlated the degree of hematuria and of blunt abdominal trauma with the results of emergency excretory urography. Urograms were obtained for 37 patients who presented with blunt abdominal trauma, no gross hematuria and at least five erythrocytes per high-power field (hpf) on microscopic urinalysis. Microscopic hematuria was defined as an erythrocyte count of more than 5 and fewer than 50 per hpf. Major trauma was defined as shock (systolic blood pressure of less than 90 mm Hg), fracture of the lumbar spine, the pelvis or the lower ribs, ecchymosis in the flank or acute abdominal injury. Contusions and small subcapsular hematomas were defined as nonsignificant renal injuries; all other renal injuries were defined as significant. Of 17 patients with minor blunt abdominal trauma 14 had fewer than 50 erythrocytes per hpf; none of these had a significant renal injury, whereas 1 of the 3 with more than 50 erythrocytes per hpf did have a significant injury. Of 20 patients with major trauma 5 had a significant renal injury. The authors conclude that microscopic hematuria associated with blunt abdominal trauma but without shock or major nongenitourinary injury does not warrant routine excretory urography.     

Hydronephrotic kidney: pediatric three-dimensional US for relative renal size assessment--initial experience

PURPOSE: To prospectively evaluate accuracy of three-dimensional (3D) ultrasonography (US) for assessment of relative renal size in infants and children with hydronephrosis. MATERIALS AND METHODS: Informed consent was obtained from parents and also from children who were older than 8 years. Study was approved by ethics committee. Two-dimensional (2D) US, 3D US, and scintigraphy were performed in 40 patients with hydronephrosis (age range, neonate to 16 years; seven girls, 33 boys) without acute renal disease. Twenty patients also underwent magnetic resonance (MR) urography. US and MR urography were performed by one experienced pediatric radiologist; 3D US and MR urographic volume calculations were performed by specifically trained radiologists. Three-dimensional US was performed with integrated 3D volume probes or external system based on electromagnetic positioning devices. At 2D US, kidney volume was calculated with application of ellipsoid equation. At MR urography and 3D US, real renal parenchymal volume was calculated with subtraction of dilated collecting system. Split renal function was assessed with static renal scintigraphy. Three-dimensional US results were graded with respect to image quality and compared with results of 2D US, scintigraphy, and MR urography by using mean difference percentage and standard deviation of the difference. All investigations were performed with blinding. Inter- and intraobserver variability were calculated with coefficient of variation. RESULTS: In 76 of 80 kidneys, 3D US image of diagnostic quality was obtained. Three-dimensional US volume measurements compared well with MR urographic measurements (mean difference, -2.5% +/- 7.8 [standard deviation] vs 25.8% +/- 32.2 for 2D US) and with scintigraphically assessed split renal function (mean difference, 1.2% +/- 9.2 vs 15.9% +/- 43.8 for 2D US). Intra- and interobserver variability were +/-6.4% and +/-9.9%, respectively. CONCLUSION: Initial experience with renal 3D US indicates that it is an accurate method for assessment of renal parenchymal volume and relative renal size, provided there is no acute renal disease.     

Ultrasonography plus direct radiography of the abdomen in the diagnosis of renal colic: still a valid approach?]

PURPOSE: The authors analyze whether the imaging approach consisting of ultrasonography and plain film in patients with renal colic is still of value when urography is replaced by unenhanced helical CT (UHCT) in unsolved cases. MATERIAL AND METHODS: Eight hundred and three consecutive patients were investigated with US following hydration and KUB, 164 of whom (20.4%) subsequently underwent UHCT (42 with the aim of mapping the excretory pathway and 122 (15.2%) because US and KUB were not considered as fully diagnostic). RESULTS: The 42 patients with detectable ureteral stone (plus possible hydronephrosis) on KUB + US and subsequently examined by UHCT to plan interventional treatment all had a positive UHCT examination. In 62 patients the diagnosis following KUB + US was uncertain (possible stone or possible hydronephrosis) and UHCT depicted the stone and/or the hydronephrosis in 34. In 60 patients the combination of KUB + US was negative but colic recurred and UHCT was positive in 17 patients. DISCUSSION: The comparison of the present results with a previous study in which KUB and US were followed by IVU in unsolved cases underscores the value of the first approach with KUB and US. The need for further diagnostic investigations when KUB + US are either not conclusive or negative and colic recurs is also confirmed. On the basis of our present data and in agreement with the literature IVU can be safely replaced by UHCT. CONCLUSIONS: It is authors' opinion that in settings where KUB, US and UHCT are available throughout the 24 hr the approach consisting of KUB plus US and UHCT in unsolved cases can be preferred in view of its on lower cost and above all lower X-ray dose to patients as compared to UHCT as the sole investigation.     

Selective renal venography in the evaluation of a non-functioning hydronephrotic kidney.

A case is presented in which extreme hydronephrosis simulated absence of the right kidney. The hydronephrosis occurred as a result of surgical ligation of the right ureter 10 years previously. There was no visualization of the excretory system by intravenous urography or retrograde pyelography. Abdominal aortography did not show the renal artery. Selective renal venography revealed a patent venous bed with splaying and thinning of the intrarenal veins. The contribution of renal venography is discussed in clarifying cases in which the kidney and the renal artery were not visualized.     

肾盂输尿管连接部梗阻X线诊断分析

目的：回顾性分析16例肾盂输尿管连接部梗阻病因、X线、CT表现，以进一步提高对病因诊断认识，提高术前诊断准确率。方法：采用排泄性尿路造影，逆行尿路造影，CT检查诊断肾盂输尿管连接部阻梗16例。结果：所有病例均清晰显示梗阻的连接部形态特征及尿路积水情况。结论：尿路造影结合CT检查是诊断肾盂输尿管连接部梗阻病因的重要手段，对病因定性、鉴别具有重要意义，对手术治疗可提供重要信息。     

Helical CT without contrast media as alternative to other methods in urolithiasis

PURPOSE: During the last five years the use of unenhanced helical CT (HTC) has been proposed as a preliminary diagnostic approach in patients with typical renal colics or with nonspecific flank pain. The aim of this study was to describe our experience in this field. MATERIAL AND METHODS: 130 consecutive patients (82 men and 48 women, with an average age of 54 years) were studied; 94 of them presented typical renal colics, while 36 presented acute flank pain. The parameters used were: 5-mm-thick sections, a pitch of 1.6, a reconstruction interscan spacing at 3 mm, an examination area extending from the kidneys to the base of the bladder. Depending on the case, examinations were carried out using urography in the instrumental or surgical pretreatment phase, ultrasonography to check urinary dilatation and juxtavesical calculi, pyeloMR, ureteroscopic extraction, surgical operation, extracorporeal lithotripsy, and finally the expulsion of the calculi was checked. RESULTS: 81 cases of urolithiasis, 6 cases of renal abnormalities and other renal pathologies, 23 cases of extraurinary pathologies correlated to the symptoms, 5 cases of extraurinary pathologies not correlated to the symptoms and 15 normal cases, were diagnosed. The results obtained were a) a sensitivity of 96.8%, a specificity of 98.4% and a diagnostic accuracy of 97.6% in identifying ureteral calculi; b) a diagnostic accuracy of 100% in identifying urinary tract dilatation; c) a sensitivity of 100% and a specificity of 96.7% in determining the level of obstruction; d) a sensitivity of 92.9% and a specificity of 100% in determining the cause of obstruction. CONCLUSIONS: Confirming the data in the medical literature, helical CT has yielded for more reliable results than the other procedures in identifying the following: calculi, acute obstruction of the urinary tract and other urinary and extraurinary pathologies correlated to the symptoms. Therefore helical CT, where available, must be accepted as the method of preliminary evaluation in all patients with typical renal colics or with nonspecific flank pain.     

Echography in renal colic

To determine the role of sonography (US) in patients with renal colic, 40 patients were examined by means of US, plain abdominal film (PF), and intravenous pyelography (ivp). US sensitivity was 92.3% in diagnosing hydronephrosis and 75% in detecting calculi. Small calculi were correctly identified, irrespective of their chemical composition. It must be stressed how US, as compared to ivp, proved unsatisfactory in such cases as difficult visualization of the middle portion of the ureter, unsuccessful identification of acute obstructions without hydronephrosis (although the patient's hydratation may be useful in this respect), poor functional information (although there was a correlation between renal hyper-echogenicity and obstructive nephrogram). US is safe and easy to perform, and is suggested for the initial evaluation of patients with renal colic, together with PF, and as an alternative to ivp. Moreover, US is the ideal technique in the follow-up of these patients. Therefore, ivp should be performed in case of differing clinical and sonographic findings, when the calculus is not ejected within the expected time, and when surgery or lithotripsy are foreseen.     

Angiographic differential diagnosis of hydronephrosis (author's transl)]

The diagnosis of hydronephrosis is made by excretory urography with late films and retrograde pyelography. Renal arteriography in hydronephrosis permits exact evaluation of vascular supply and parenchymal thickness. In three cases selective arteriography was performed because of a non-functioning kidney or suspected space-occupying lesion. The combination of arteriogram and urogram--if necessary together with percutaneous puncture--allows to differentiate between hydronephrosis, avascular tumors, renal cysts, polycystic renal disease, renal abscess, subcapsular renal hematoma, fibrolipomatosis, xanthogranulomatous pyelonephritis, and tuberculosis.